Many heat exchange systems, as, for example, refrigeration or air conditioning systems, have components that are subject to relatively high internal pressures. As a consequence, high strength bonding methods are employed to bond components together. Brazing is a frequent technique and, as is well-known, the components to be bonded together are assembled, frequently with the aid of a fixture or jig, and then passed into a brazing oven or the like. Welding is also employed.
Within the brazing oven, the components are raised to specific temperatures for such periods of time as to effect a change of state in the braze metal while the base metal remains essentially solid to cause a brazed joint to be formed. While this technique is very satisfactory for its intended purpose, and indeed, has been employed successfully for scores of years, it is not without its potential pitfalls.
In order to get an ideal brazed bond, it is necessary that all parts be raised to a temperature above the melting point of the braze metal and yet below the melting point of the base metal; and that there be a substantial uniformity of temperature in the assembly being brazed. Where time is not of great concern, this may be relatively easy to achieve since temperature equilibrium throughout the assembly to be brazed will eventually occur over a prolonged period of time. However, in modern manufacturing techniques, it is generally desirable to minimize a length of time required for the performance of any given operation to improve efficiency of the process. Consequently, in modern brazing processes, it is desired to minimize the residence time within the brazing oven.
Furthermore, even though the base metal may not have its temperature increased to a point above its melting point, the temperature to which it is elevated during the brazing process may be sufficiently close that prolonged exposure thereto may result in sagging of the components if they are not supported appropriately within fixtures. And appropriate support may necessitate the use of unduly complicated fixtures. Welding processes have similar potential problems.
One area in which the foregoing presents a problem is in the field of automotive air conditioners. As illustrated in FIG. 1, wherein a prior art system is illustrated schematically, a vehicle may have a fire wall 10. On one side of the fire wall 10 is a passenger compartment 12 while on the opposite side is the engine compartment 14.
An evaporator shown schematically at 16 will typically be located within the passenger compartment 12 while a compressor 18, driven by the engine will be in the engine compartment 14. In the usual case, the compressor is connected to a condenser 20 located forwardly of the engine. Other components such as fans, expansion valves, belts, controls and the like have been omitted for clarity.
In any event, to provide an operative system, it is necessary to connect to the outlet of the condenser 20 to the inlet 24 of the evaporator 16 through the fire wall 10 via a relatively small diameter liquid refrigerant or condensate conduit 26. The outlet 28 of the evaporator is connected through the fire wall 10 to the inlet 30 of the compressor via a relatively large refrigerant vapor conduit 32.
To facilitate installation within the automobile, the liquid refrigerant conduit 26 is made in two segments 34 and 36. Similarly, the refrigerant vapor conduit is made in two segments 38 and 40. The segments 34 and 38 are on the passenger compartment side of the fire wall 10 while the segments 36 and 40 are on the engine compartment side of the fire wall.
A mounting block or fixture 42 may be secured to the fire wall 10 in an opening therein and receives the ends of the conduit segments 34 and 38 which are brazed or welded to interior ports therein. The conduit segments 36 and 40 terminate in respective block fittings 46 and 48 which are secured as by bolts 50 to the block 42 to establish fluid communication and a sealed relation between the segments 34 and 36 on the one hand and the segments 38 40 on the other.
Typically, the various components are bonded together as by welding or brazing. The difference in mass between the block 42 and the other components of this system can give rise to the previously mentioned problems during a welding or brazing operation.
The present invention is directed to provision of a fitting that avoids such difficulty and yet maintains the same ease of assembly of the components within, for example, an automotive air conditioning system.